Effect of alloying degree in PtSn catalyst on the catalytic behavior for ethanol electro-oxidation

Carbon-supported binary PtSn catalysts with varied alloying degree were synthesized in different processes and denoted as PtSn/C-B, PtSn/C-EG and PtSnO2/C, respectively. X-ray diffraction (XRD) characterizations showed that PtSn/C-B catalyst displayed the highest alloying degree, while PtSnO2/C catalyst had the lowest one among these samples. X-ray photoelectron spectroscopy (XPS) results revealed that the non-alloyed Sn existed in an oxidized state on the surfaces of these catalysts. By evaluating the electro-catalytic activity and analyzing the final products of ethanol oxidation reaction (EOR) on these catalysts, it was found that PtSnO2/C catalyst enhanced the products yield of acetic acid products and PtSn/C-B catalyst promoted the entire activity for EOR. It was proposed that non-alloyed SnO2 species enhanced the bi-functional mechanism, whereas PtSn alloy phase strengthened the electronic effect of PtSn/C catalyst.